WO 03/106825 A1 discloses a method for operating a liquid-cooled internal combustion engine, in which an electric coolant pump is briefly operated for a period of time following detection of a cold start and after expiration of the period of time is always deactivated again. For as long as a coolant temperature is below a threshold value, the coolant pump is then activated with alternating direction of delivery. As soon as the coolant temperature has reached the threshold value, the coolant pump is activated in such a manner that a continuous coolant flow is obtained, and a control valve is actuated as a function of the coolant temperature in order to flow through a bypass with an oil-coolant heat exchanger and at higher coolant temperatures and a radiator.